Ozone oxidation of antidepressants in wastewater –Treatment evaluation and characterization of new by-products by LC-QToFMS

• Published in: BMC chemistry 2013-01, Vol.7 (1), p.15-15, Article 15
• Main Authors: Lajeunesse, André, Blais, Mireille, Barbeau, Benoît, Sauvé, Sébastien, Gagnon, Christian
• Format: Article
• Language: English
• Subjects: Antidepressants; Aqueous solutions; Biosolids; Chemicals; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Effluents; Environmental and Energy Chemistry; Experiments; Free radicals; LC-MS/MS; Mass spectrometry; Membrane reactors; Metabolites; Oxidation; Ozone; Pharmaceuticals; Research Article; Sewage treatment plants; Side-products; Sludge; Water treatment
• ISSN: 1752-153X; 1752-153X; 2661-801X
• DOI: 10.1186/1752-153X-7-15

Background The fate of 14 antidepressants along with their respective N -desmethyl metabolites and the anticonvulsive drug carbamazepine was examined in a primary sewage treatment plant (STP) and following advanced treatments with ozone (O 3 ). The concentrations of each pharmaceutical compound were determined in raw sewage, effluent and sewage sludge samples by LC-MS/MS analysis. The occurrence of antidepressant by-products formed in treated effluent after ozonation was also investigated. Results Current primary treatments using physical and chemical processes removed little of the compounds (mean removal efficiency: 19%). Experimental sorption coefficients (K d ) of each studied compounds were also calculated. Sorption of venlafaxine, desmethylvenlafaxine, and carbamazepine on sludge was assumed to be negligible (log K d ≤ 2), but higher sorption behavior can be expected for sertraline (log K d ≥ 4). Ozonation treatment with O 3 (5 mg/L) led to a satisfactory mean removal efficiency of 88% of the compounds. Screening of the final ozone-treated effluent samples by high resolution-mass spectrometry (LC-QqToFMS) did confirm the presence of related N -oxide by-products. Conclusion Effluent ozonation led to higher mean removal efficiencies than current primary treatment, and therefore represented a promising strategy for the elimination of antidepressants in urban wastewaters. However, the use of O 3 produced by-products with unknown toxicity.